From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:37839) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ggthf-0003tC-M7 for qemu-devel@nongnu.org; Tue, 08 Jan 2019 10:54:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ggthf-0006hN-1c for qemu-devel@nongnu.org; Tue, 08 Jan 2019 10:54:07 -0500 Date: Tue, 8 Jan 2019 16:53:55 +0100 From: Kevin Wolf Message-ID: <20190108155355.GH11492@linux.fritz.box> References: <20181114145857.19720-1-berto@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181114145857.19720-1-berto@igalia.com> Subject: Re: [Qemu-devel] [PATCH v2] qcow2: Assert that refcount block offsets fit in the refcount table List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alberto Garcia Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz , Eric Blake Am 14.11.2018 um 15:58 hat Alberto Garcia geschrieben: > Refcount table entries have a field to store the offset of the > refcount block. The rest of the bits of the entry are currently > reserved. > > The offset is always taken from the entry using REFT_OFFSET_MASK to > ensure that we only use the bits that belong to that field. > > While that mask is used every time we read from the refcount table, it > is never used when we write to it. Due to the other constraints of the > qcow2 format QEMU can never produce refcount block offsets that don't > fit in that field so any such offset when allocating a refcount block > would indicate a bug in QEMU. > > Signed-off-by: Alberto Garcia > Reviewed-by: Eric Blake Thanks, applied to the block branch. Kevin